An uninterruptible power supply (UPS) device that is equipped with a storage battery and capable of continuously supplying electric power from the storage battery to a connected device during a predetermined period of time without power interruption even when electric power from an input power source is interrupted is known. A technique of extending such a power supply device to a consumer unit and supplying electric power to consumers when an abnormality such as power outage or insufficient capacity of a storage battery occurs in power supply has been proposed (see Patent Literatures 1 and 2).